1. Field of the Invention
The invention relates to an exercise apparatus, more particularly to an exercise apparatus with a resistance adjustment device for adjusting magnitude of resistance to rotation of a flywheel.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional exercise apparatus 10 is shown to include a front support frame 11 having two fixed upright rods 111, a rear support frame 12, a bottom connecting rod 13 interconnecting the front and rear support frames 11, 12, a seat assembly 14 mounted adjustably on the rear support frame 12, a handle assembly 15 mounted on the front support frame 11, a flywheel 16 mounted rotatably between the upright rods 111 of the front support frame 11, a pedal unit 17 mounted on the rear support frame 12 for actuating rotation of the flywheel 16, and a resistance adjustment unit 20 for adjusting magnitude of resistance to rotation of the flywheel 16.
The adjustment unit 20 includes a fixed seat 21 mounted fixedly between the upright rods 111 and located above the flywheel 16, a pivot shaft 22 mounted on the fixed seat 21, two brake arms 23, 24 sleeved rotatably on the pivot shaft 22, two brake shoes 25 connected respectively to the brake arms 23, 24 and flanking the flywheel 16, an adjustment knob 26 disposed operably on the front support frame 11, and a cable 27 disposed between the adjustment knob 26 and the brake arms 23, 24. When the knob 26 is operated to loosen or tighten the cable 27, the brake arms 23, 24 are actuated to move the brake shoes 25 away from or toward the flywheel 16 so that adjustment of the magnitude of the resistance to the rotation of the flywheel 16 can be effected.
Although the adjustment unit 20 of the conventional exercise apparatus 10 can achieve its intended purpose, it has the following disadvantages:
1. The adjustment unit 20 is not designed to have an instant brake function. During pedaling exercise, two pedals 171 (only one is visible in FIG. 1) of the pedal unit 17 cannot stop rotation unless the flywheel 16 stops so that injury to users due to movement of the pedals 171 cannot be avoided.
2. Since each of the brake shoes 25 is connected to the respective one of the brake arms 23, 24 by means of a single screw-and-nut fastener 251, the brake shoes 25 can easily deflect so that contact with the flywheel 16 is not complete, thereby leading to ineffective adjustment of the magnitude of resistance to flywheel rotation.
3. Since tolerances exist during production and assembly of the brake arms 23, 24, and since the brake shoes 25 are directly connected to the brake arms 23, 24, when positions of the brake arms 23, 24 deflect, the brake shoes 25 cannot accommodate the position deviation. As such, the brake shoes 25 cannot contact the flywheel 16 completely.
Therefore, the main object of the present invention is to provide a resistance adjustment device for an exercise apparatus that permits adjustment of magnitude of resistance to flywheel rotation at different speeds and that can permit an instant brake so as to enhance safety.
Another object of the present invention is to provide a resistance adjustment device for an exercise apparatus which includes brake shoes that can be brought into complete contact with a flywheel so as to effectively brake the flywheel.
According to this invention, a resistance adjustment device is to be adapted for use with an exercise apparatus. The exercise apparatus includes a front support frame having two fixed upright rods, a rear support frame, a handle assembly mounted on the front support frame, a flywheel mounted rotatably between the upright rods of the front support frame, a seat assembly mounted on the rear support frame, and a pedal unit for actuating rotation of the flywheel. The resistance adjustment device comprises first and second swing arms, two biasing units, two brake devices, a first adjustment unit, and a second adjustment unit. The first and second swing arms are adapted to be connected pivotally and respectively to the upright rods of the front support frame, are adapted to flank the flywheel, and are rotatable toward and away from the flywheel. Each of the biasing units is adapted to be disposed between a respective one of the upright rods and a respective one of the first and second swing arms so as to bias the first and second swing arms to rotate away from the flywheel. The brake devices are connected respectively to the first and second swing arms, and are located on two sides of the flywheel. The first adjustment unit has an adjustment knob adapted to be mounted rotatably on the front support frame, a tubular first guiding member connected fixedly to the first swing arm, a first fixing member connected fixedly to the second swing arm, and a first cable fastened to the adjustment knob at one end and to the first fixing member at another end. The first cable has an intermediate portion extending through the first guiding member. The second adjustment unit includes a brake lever adapted to be mounted operably on the handle assembly, a tubular second guiding member connected fixedly to the second swing arm, a second fixing member connected fixedly to the first swing arm, and a second cable fastened to the brake lever at one end and to the second fixing member at another end. The second cable has an intermediate portion that extends through the second guiding member. When the adjustment knob is operated, the first cable can be loosened and pulled so that the first and second swing arms can move the brake devices away from and toward the flywheel, thereby adjusting magnitude of resistance to rotation of the flywheel. When the brake lever is operated, the second cable can be swiftly pulled so that the first and second swing arms can move the brake devices toward the flywheel so as to clamp the flywheel to effect an instant brake.